This dichotomy has had a marked impact in neuroscience, where brain regions have been accorded different roles in these two kinds of learning, and where an influential line of research has focused on how the two forms of learning may trade off against one another [1]}, [2]}, [3]}, [4]}, [5]}. Deep RL opens up a new vantage point on the relationship between model-free and model-based RL. For example, in AlphaGo and its successor systems [6]}, [7]}, [8]}, model-based planning is guided in part by value estimates and action tendencies learned through model-free RL. Related interactions between the two systems have been studied in neuroscience and psychology [9]}, [10]}.
